In conventional fuel cell systems including fuel cells, not all supplied hydrogen is used for the cell reaction. Accordingly, the fuel cell system adopts a circulation system for effectively using the discharged and unreacted hydrogen by sending it back to the fuel cell again; a gas-liquid separator is placed in the circulation system, and it removes moisture from a gas-liquid mixture fluid in which exhaust gas discharged from the fuel cell and water generated by the cell reaction in the fuel cell are mixed together.
Minute amounts of impurities dissolving from, for example, piping parts of the fuel cell or the system exist in the gas and water flowing through the hydrogen circulation system. Also, impurities in the air drawn in from outside on the cathode side may enter a passage to the system, pass through an electrolyte membrane, and be mixed in the hydrogen circulation system. In particular, if metal ions exist in the impurities dissolving from, for example, piping parts of the fuel cell or the system, there is the possibility of the functions of the fuel cell itself being degraded or the service life of the fuel cell being shortened. In addition, the water generated in the fuel cell may become acidic. Accordingly, a method for inhibiting deterioration of the fuel cell due to, for example, the generated water and gas by placing an ion exchanger in the hydrogen circulation system has been adopted.
Recently, a solid polymer fuel cell system with an ion removal unit has been introduced, and the ion removal unit removes ions contained in water generated by the fuel cell and accompanied by an exhaust gas, and is placed on the side closer to a solid polymer fuel cell of at least one exhaust pipe from which the water generated by the fuel cell is discharged. It is disclosed that in this solid polymer fuel cell system, fluoride ions are removed using an ion exchange resin as a means for removing ions from the water. (See, for example, Patent Document 1).
Also, there is a fuel cell generator in which an impurity removal member is located in an exhaust manifold on the air side. (See, for example, Patent Document 2).
[Patent Document 1] JP2002-313404 A
[Patent Document 2] JP9-312166 A